Prewire for Solar - what kind of wire?

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Prewire for Solar - what kind of wire?

Postby Boreal » Tue Jun 06, 2017 11:55 pm

I'm just getting to installing the roof and skin (aluminum on ply) of my home-built teardrop. I want to prepare for the eventuality of installing solar panels on the roof, so I am reinforcing struts and structure. I want to pre-wire the leads from the the panels to the tongue-box, where the batteries and electronics will be stored.

So what wire can I pre-install? I had thought 12 of 10 ga. would be adequate, but then I saw this stuff: https://www.amazon.ca/Signstek-Double-Extension-Connectors-25-Feet/dp/B00JTM2U6M/ref=pd_lutyp_wish_2_4?_encoding=UTF8&pd_rd_i=B00JTM2U6M&pd_rd_r=CD4JFEMKFA70KAS408HH&pd_rd_w=VvuAw&pd_rd_wg=uQ59p&psc=1&refRID=CD4JFEMKFA70KAS408HH

Signstek AWG 10 Double Layer MC4 PV Solar Cable Extension for Solar Panels with Solar Male and Female Connectors, 25-Feet

Not sure I'll need the connectors, and aside form that, it's 10 ga. Should I be using this stuff, or just run some regular, 10ga speaker wire?
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Re: Prewire for Solar - what kind of wire?

Postby lrrowe » Wed Jun 07, 2017 8:12 am

I believe in ovebuilding and bought 10 gauge wire as it was the largest I could wire to my BRAT comtroller and these connectors. It offered me the least amount of voltage loss for this setup.

https://www.amazon.com/gp/product/B00A8 ... UTF8&psc=1.

Buying wire in 100 ft lengths allowed me to be flexible in where I ran the wire.
Bob

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Re: Prewire for Solar - what kind of wire?

Postby tony.latham » Wed Jun 07, 2017 10:32 am

What size panel(s) are you contemplating? My reaction, without knowing details, is that 10 gauge isn't needed.

Here's a calculator to determine you wire needs:

http://www.freesunpower.com/wire_calc.php

Tony
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Re: Prewire for Solar - what kind of wire?

Postby MtnDon » Wed Jun 07, 2017 10:44 am

Most PV panels come supplied with short wires with MC4 connectors, a M and an F to help keep polarity straight when there is more than 1 panel. Thet are weatherproof connectors. It seems to me retaining the connectors makes sense in case somethingneeds to be serviced. It also seems that most MC4 wire sets I've seen are 10 gauge. Maybe that simplifies the choice. You can never have too large a wire in the primary panel wires, IMO.
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Re: Prewire for Solar - what kind of wire?

Postby lrrowe » Wed Jun 07, 2017 1:15 pm

tony.latham wrote:What size panel(s) are you contemplating? My reaction, without knowing details, is that 10 gauge isn't needed.

Here's a calculator to determine you wire needs:

http://www.freesunpower.com/wire_calc.php

Tony

In my case, 12v, 9amps, 20 ft calculates out to 10 awg.
Bob

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Re: Prewire for Solar - what kind of wire?

Postby Shadow Catcher » Wed Jun 07, 2017 7:35 pm

I used a Perko marine deck through plug https://www.amazon.com/Perko-1190DP0CHR-Marine-Watertight-Connection/dp/B00144B67C which limited me to 10 ga, however I have a high voltage panel so some voltage drop was not a concern.
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Re: Prewire for Solar - what kind of wire?

Postby Boreal » Thu Jun 08, 2017 11:23 pm

OK...Remember I'm prepping for a future installation. SO I have hardpoints to install racks and cross braces and angle-tilting thingies to point the panels and such.

I will pre-install 10 ga wire through the roof and into the tongue box, where the electronics will be located.

Does anyone have a suggestion as to how to run the wire through the 1/8" roof skin (and the 8oz fiberglass cloth that will be topping it) to keep a bombproof weatherproof seal?

Also, I presume I can buy a connector to crimp or solder onto that 10 ga wire to connect it to the solar panels.
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Re: Prewire for Solar - what kind of wire?

Postby H.A. » Fri Jun 09, 2017 7:04 am

Ifru.
Last edited by H.A. on Thu Jul 06, 2017 4:06 am, edited 1 time in total.
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Re: Prewire for Solar - what kind of wire?

Postby Boreal » Fri Jun 09, 2017 7:35 am

H.A. wrote:If using premade MC4 cables, I suggest a "cable clam" type of liquid tight pass thru.
Otherwise, most other pass-thru options require your MC4 connectors be installed after the wire is passed thru.


I was planning to use regular cable and add the connectors after the fact.

I will have to Google "liquid clam type" of pass thru. But what are the other pass thru options?
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Re: Prewire for Solar - what kind of wire?

Postby H.A. » Sun Jun 11, 2017 12:47 am

Boreal wrote:I was planning to use regular cable and add the connectors after the fact.
I will have to Google "liquid clam type" of pass thru. But what are the other pass thru options?

Aside from a hole thru & blob of caulking to seal up... :banana: You can use gland type pass thru. Mostly those are found for round single conductor/cable only, But they are available for flat cables or multiple round conductors also.
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Re: Prewire for Solar - what kind of wire?

Postby Boreal » Sun Jun 18, 2017 9:41 pm

Here's what I've decided to do.

10 Ga. wire comes in single conductor (where I get it from). So I've pre-wired a double run of single from a spot - carefully marked and recorded - on the roof. When and if I need to run the solar connection, I'll drill through the roof at the prescribed location and, if there's any justice in the world whatsoever, fish it out. Then figure out how to seal the hole, yadda yadda yadda.

But I did have a thought, which is dangerous at times when I've had a few tequila and OJ and fresh lime juice, that it just might be better to run any supply lines above ground, so to speak, and forgoe any piercing of the precious membrane of life.

Oh well, I'll rethink that when I get to that point. In the meanwhile, the lines are run and sitting, Quietly, for their moment.
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